Process of making tri-alkali phosphate.



UNITED STATES" PATENT OFFICE. T

EMEBsoN H. s'rmck'tnn, oi YORK, a. Y., AssIcno'n 'ro GENERAL CHEMICALCOMPANY, on NEW YORK, Y., a ooRPonA'rIou-or NEW YORK.

success or mamas mar-Arum mosrnars.

Specification of Letters Iatent.

Patented Sept. 3, 1912.

1,037,837. I Rd Brewing. Application filed Mare-h 16, 1911. Serial No.614,842.

To all whom 'it' may comma:

Be it known that LEMnRsoN H. STRIOK LER, a citizen of the United States,and resident of New York city, New York,have invented certain new anduseful Improvements in Processes of Making Tri-Alkali Phosphates, ofwhich the following is a specification. I a V p In my United StatesLetters Patent No.

744,128 of November 17, 1903, I disclosed a new process of makingtri-sodium phosphate by treating material containing phosphoric acidsuch as calcium phosphate in the form of so called phosphat'errock withniter cake and after. removal of the calcium sulfate, suitably heatingthe remaming l1q uor with carbonaceous material such as coal.

I havenow invented an improvement on said. process which consistsbroadly in treating phosphoric acid substantially free from calciumsulfates and other sulfates,

with the sulfate of an alkali such as potassium sulfate or sodiumsulfate and then suitably heating that result with carbonaceous materialsuch as coal so as to obtain tri potassium or tri-sodium-phosphate' asthe case may be.

This, my improved process, has the following advantages over my formerprocess: 1. It permits the product-ion of other trialkali phosphatessuch as potassium triphosphate as well as of sodium tri-phosphate. 2. Itpermits of the manufacture of greater amounts of product with the samemachinery, manual help and fuel. The lattcr becomes evident upon thefollowing con-- siderations: Practice has shown that under my formerprocess the liquor resulting from the digestion of phosphate rock withniter cake solution contains approximately 7.5% of phosphoric anhydrid(P20 and that this cannot be increased without making the processdiflicult or almost impossible as a manufacturing operation. In my newprocess, starting with a phosphoric acid containing 20% or 'thereaboutof P 0 (which is an acid of a strength commercially obtainable withoutevaporation by digesting phosphate rock with sulfuric acid) 'and addingthereto the requisite amount of say sodium sulfate, a liquor is obtainedwhich contains by weight substantially 12.5% phosphoric anhydrid (P 0The mixture so resultmg from 100 parts of the above phosphoric acid andamounting to 160 parts, contains off in the subsequent operationsproducing 46 parts of finished furnaced product whereas in my formerprocess for every 46 parts .of finished product 246 parts of water haveto be driven off in other words,- in my new process only about theamount of water as to be 'driven ofi as in my former process, and, fromequal bulks of material to be prepared for treatment with carbonaceousmaterial my new process enables me to pro duce about twice as muchfinished product as is produced by my former process.

In the following I production of tri-potassi'um phosphate and oftri-sodium phosphate. These examples are forpurposes of illustrationonly and my new process can be variedwithout departing from myinvention. -The parts are by weight:

E wampl'e l.-Produc tion' of ind-sodium phosphata-Digest groundphosphate rock in sulfuric acid 35 1%., and separate the undissolvedcalcium sulfate by filtration. To the crude phosphoric acid solutionthus obtained add solid sodium sulfate, such as salt cake of goodaverage quality, in the proportion of approximately 3 parts Na SO -to 1part- P O Evaporate the mixture, add coal and furnace until the reactionis complete and tri-sodium phosphateis obtained. The proportions ofphosphate rock and sulfuric acid must be determined empirically for eachrock to get the best results. When usin a high test .rock and salt cakethe proportions by weight are approximately 400 parts phosphate rock,300 parts sulfuric acid 66 B. diluted to Ema-mple II.-P1'0ducti0n. 0ftri-potas- .sz'um phosphate..-VVhen making tri-potas-' sium phosphateproceed as in Example I, but add potassium sulfate in place of saltcake. Using a 90% potassium sulfate the proportions by weight areapproximately: 400 parts phosphate rock, 300' parts sulfuric acid 66diluted to 35 136., 525 parts potassium sulfate, 200- parts coal.

Iclaim:

1. Process of making a tri-allcali phosphate which consists in mixingphosphoric acid. substantially free from sulfates with the sulfate of analkali and carbonaceous material and furnacing the result until atri-alkali phosphate is produced, substantially as and for the purposedescribed.

2. Process of making tri-sodium phosgive examples for the phate whichconsists in mixing phosphoric acid substantially free from sulfates withsulfate of sodium and carbonaceous material and furnacing the resultuntil trisodium phosphate is produced, substantially as and for thepurpose described.

3. The process of making a tri-alkali phosphate which consists intreating phosphate rock with sulfuric acid, removing the calciumsulfate, and furnacing the resulting product with an alkali sulfate andearbonaceous material until a tri-alkali phos phate is produced,substantially as and for the purpose described.

4. The process of making tri-sodium phosphate which consists in treatingphosphate rock with sulfuric acid, removing the calcium sulfate andfurnacing the so resulting product with sodium sulfate and carbonaceousmaterial until tri-sodium phosphate is produced, substantially as andfor the purpose described.

In witness whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

EMERSON H. STBICKLER Witnesses HOMER lV. HiLLYuR, JOHN A. KEHLENBECK.

